Rotary electric machine control device

Abstract

Providing a technique capable of executing fail-safe control even when power supply to an inverter control device is cut off SOLUTION: An inverter including a plurality of series circuits each including an upper-stage-side switching element and a lower-stage-side switching element, the inverter being configured to convert electric power between a direct-current power supply and an alternating-current rotary electric machine; The control circuit includes a processor that causes the inverter to perform one of shutdown control and active short-circuit control in accordance with a rotational speed of the rotating electrical machine, a buffering circuit that buffers information indicating control in accordance with the rotational speed of the rotating electrical machine, and a switching circuit that causes the inverter to perform the control indicated by the information buffered in the buffering circuit when power supply to the processor is stopped.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rotary electric machine control device. [Background technology]

[0002] Conventionally, there is known a technique for performing fail-safe control in an inverter that converts power between a DC power source and an AC rotating electric machine. For example, Patent Document 1 discloses a configuration in which an inverter control device performs shutdown control or active short circuit control in response to the rotational speed ω of the rotating electric machine. Patent Document 1 further discloses a backup power supply that can supply power to the inverter control device when the power supply to the inverter control device is interrupted. With this configuration, even when the power supply to the inverter control device is interrupted, it is possible to perform shutdown control or active short circuit control in response to the rotational speed ω of the rotating electric machine. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6418252 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional technology, even if the power supply to the inverter control device is interrupted, a backup power supply capable of supplying the same amount of power as that which was interrupted is required so that the inverter control device can perform the same control as before the power supply was interrupted. Since providing such a backup power supply leads to increased costs, it is preferable to be able to perform fail-safe control more simply.

[0005] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a technology that can execute fail-safe control with a simple configuration when the power supply to an inverter control device is cut off. [Means for solving the problem]

[0006] In order to achieve the above object, the rotating electric machine control device comprises an inverter having a plurality of series circuits of upper-stage switching elements and lower-stage switching elements, and converting power between a DC power source and an AC rotating electric machine, and a control circuit controlling the inverter, wherein the control circuit comprises a processor that causes the inverter to perform either shutdown control that turns off all of the upper-stage switching elements and the lower-stage switching elements, or active short circuit control that turns on one stage of the upper-stage switching elements and the lower-stage switching elements and turns off the other stage, depending on the rotational speed of the rotating electric machine, a buffering circuit that buffers information indicating whether the control depending on the rotational speed of the rotating electric machine is the shutdown control or the active short circuit control, and a switching circuit that causes the inverter to perform the control indicated by the information buffered in the buffering circuit when power supply to the processor is stopped.

[0007] That is, the rotating electric machine control device buffers information indicating whether the control corresponding to the rotational speed of the rotating electric machine is shutdown control or active short circuit control. Because the buffering is realized by a buffering circuit separate from the processor, even if the power supply to the processor is stopped, the switching circuit can control the inverter based on the buffered information. The buffered information indicates whether the control to be executed corresponding to the rotational speed of the rotating electric machine immediately before the power supply to the processor was stopped was shutdown control or active short circuit control.

[0008] Therefore, the buffered information indicates whether the control selected depending on the rotational speed of the rotating electric machine immediately before the power supply to the processor was stopped is shutdown control or active short circuit control. Immediately after the power supply to the processor is stopped, it is expected that the rotational speed of the rotating electric machine will not change significantly from the speed immediately before the power supply was stopped. Therefore, by having the inverter perform the control indicated by the buffered information, it is possible to perform control depending on the rotational speed of the rotating electric machine. Therefore, it is possible to perform control depending on the rotational speed of the rotating electric machine without restoring the power supply to the processor using a backup power supply or the like, and it is possible to perform fail-safe control with a simple configuration. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a diagram illustrating a rotary electric machine control device. [Figure 2] 10A and 10B are diagrams illustrating an example of a battery current and a DC link voltage when shutdown control is being performed. [Figure 3] FIG. 2 is a diagram illustrating an example of a buffering circuit and a switching circuit. [Figure 4] FIG. 10 is a diagram illustrating the operation of a D latch circuit. [Figure 5] 4 is a timing chart showing an example of time-series changes in control states and signals at various parts of the circuit. [Figure 6] 4 is a timing chart showing an example of time-series changes in control states and signals at various parts of the circuit. [Figure 7] 4 is a timing chart showing an example of time-series changes in control states and signals at various parts of the circuit. [Figure 8] 4 is a timing chart showing an example of time-series changes in control states and signals at various parts of the circuit. DETAILED DESCRIPTION OF THE INVENTION

[0010] Here, the embodiments of the present invention will be described in the following order. (1) Configuration of a rotating electrical machine control device: (2) Example of operation: (3) Other embodiments:

[0011] (1) Configuration of a rotating electrical machine control device: A rotating electric machine control device according to this embodiment will be described with reference to the drawings. Fig. 1 is a diagram showing a circuit including a rotating electric machine control device according to one embodiment of the invention. The rotating electric machine control device includes an inverter 10 and a control circuit 20. The inverter 10 is a power conversion device that is connected to a high-voltage DC power supply 30 and also to a rotating electric machine 40, and converts power between the DC of the high-voltage DC power supply 30 and the multiple-phase AC (here, three-phase AC) of the rotating electric machine 40.

[0012] In this embodiment, the rotating electric machine 40 serves as a driving power source for a vehicle such as a hybrid vehicle or an electric vehicle. In this embodiment, the rotating electric machine 40 is a rotating electric machine that operates on multi-phase AC (here, three-phase AC) and functions as both an electric motor and a generator. That is, the rotating electric machine 40 rotates on AC power obtained by converting DC power from a high-voltage DC power supply 30 via an inverter 10, and the vehicle is driven by the power generated by this rotation (power running). The rotating electric machine 40 also rotates on rotational driving force transmitted from an internal combustion engine or wheels provided in the vehicle, and when AC power is generated by this rotation, this AC power is converted into DC power via the inverter 10. The converted DC power is charged into the high-voltage DC power supply 30 (regeneration).

[0013] The high-voltage DC power supply 30 is configured by, for example, a secondary battery (battery) such as a nickel-metal hydride battery or a lithium-ion battery, or an electric double layer capacitor. The high-voltage DC power supply 30 that supplies power to the rotating electric machine 40 is a high-voltage, large-capacity DC power supply. The rated power supply voltage of the high-voltage DC power supply 30 is, for example, 200 to 400 V. Because the rotating electric machine 40 is an AC rotating electric machine, an inverter 10 that converts power between DC and AC (here, three-phase AC) is provided between the high-voltage DC power supply 30 and the rotating electric machine 40, as described above. The high-voltage DC power supply 30 can supply power to the rotating electric machine 40 via the inverter 10, and can also store power generated by the rotating electric machine 40. A contactor 15 and a smoothing capacitor 14 that smooths voltage generated by regeneration are provided between the inverter 10 and the high-voltage DC power supply 30. The smoothing capacitor 14 stabilizes the DC voltage (DC link voltage Vdc) that fluctuates in accordance with fluctuations in the power consumption of the rotary electric machine 40.

[0014] A contactor 15 is provided between the high-voltage DC power supply 30 and the smoothing capacitor 14. That is, the inverter 10 and the smoothing capacitor 14 are connected to the high-voltage DC power supply 30 via the contactor 15, which cuts off the supply of power when in an open state, as will be described later. The contactor 15 can electrically disconnect the electric circuit system (smoothing capacitor 14, inverter 10) of the rotary electric machine drive device from the high-voltage DC power supply 30.

[0015] In this embodiment, the contactor 15 is a mechanical relay that opens and closes based on a command from a vehicle control unit (not shown), which is one of the highest-level control devices of the vehicle, and is referred to as, for example, a system main relay (SMR). When the ignition key (IG key) of the vehicle is in the on state (enabled state), the contacts of the SMR are closed and the contactor 15 is in a conductive state (connected state), and when the IG key is in the off state (disabled state), the contacts of the SMR are opened and the contactor 15 is in a non-conductive state (open state). That is, when the contactor 15 is in the connected state, the high-voltage DC power supply 30 and the inverter 10 (and the rotating electric machine 40) are electrically connected, and when the contactor 15 is in the open state, the electrical connection between the high-voltage DC power supply 30 and the inverter 10 (and the rotating electric machine 40) is interrupted.

[0016] The inverter 10 is a circuit that includes a plurality of series circuits each including upper-stage switching elements 11a to 11c and lower-stage switching elements 11d to 11f, and converts power between a high-voltage DC power supply 30 and an AC rotating electric machine 40. Specifically, of the plurality of switching elements, the switching elements electrically connected to the positive electrode of the high-voltage DC power supply 30 are referred to as upper-stage switching elements 11a, 11b, and 11c. Also, of the plurality of switching elements, the switching elements electrically connected to the negative electrode of the high-voltage DC power supply 30 are referred to as lower-stage switching elements 11d, 11e, and 11f.

[0017] The upper-stage switching elements 11a to 11c and the lower-stage switching elements 11d to 11f are preferably power semiconductor elements capable of operating at high frequencies. Examples of such elements include an IGBT (Insulated Gate Bipolar Transistor), a power MOSFET (Metal Oxide Semiconductor Field Effect Transistor), a SiC-MOSFET (Silicon Carbide-Metal Oxide Semiconductor FET), a SiC-SIT (SiC-Static Induction Transistor), and a GaN-MOSFET (Gallium Nitride-MOSFET). In this embodiment, the upper-stage switching elements 11a to 11c and the lower-stage switching elements 11d to 11f are IGBTs.

[0018] The inverter 10 is configured with a bridge circuit having arms corresponding to the respective phases. The inverter 10 has arms for three AC phases, and each arm is configured with a series circuit of one of upper-stage switching elements 11a to 11c and one of lower-stage switching elements 11d to 11f. Specifically, as shown in Fig. 1, in the inverter 10, one arm is configured by two switching elements connected in series between the positive and negative sides of a high-voltage DC power supply 30.

[0019] For example, the upper-stage switching element 11a and the lower-stage switching element 11d form a series circuit, which constitutes one arm. Similarly, the upper-stage switching element 11b and the lower-stage switching element 11e form a series circuit, which constitutes one arm, and the upper-stage switching element 11c and the lower-stage switching element 11f form a series circuit, which constitutes another arm. In the case of three-phase AC, this series circuit (one arm) is connected in parallel to three circuits (three phases). In other words, a bridge circuit is formed in which a set of series circuits (arms) corresponds to each of the coils corresponding to the U-phase, V-phase, and W-phase of the rotating electric machine 40.

[0020] The intermediate points of the series circuits (arms) of the paired switching elements of each phase, i.e., the connection points between the upper-stage switching elements 11a to 11c and the lower-stage switching elements 11d to 11f, are electrically connected to the three-phase coils of the rotary electric machine 40. Diodes 13a to 13f (freewheel diodes) are electrically connected in parallel to each switching element, with the forward direction being from the negative pole to the positive pole (from the lower stage to the upper stage).

[0021] The control circuit 20 causes the switching elements constituting the inverter 10 to perform switching operations. Furthermore, when an undesirable event such as an overcurrent or an overvoltage occurs in the rotary electric machine drive device, the control circuit 20 performs fail-safe control to cause the inverter 10 to perform fail-safe operations. In this embodiment, the control circuit 20 selectively performs active short circuit control and shutdown control as this fail-safe control.

[0022] The control circuit 20 includes a processor 21, a buffering circuit 22, a switching circuit 23, and drive circuits 24a to 24c, 24d to 24f. The control circuit 20 operates using power supplied from a low-voltage DC power supply 32. Specifically, the low-voltage DC power supply 32 is connected to a drive power supply circuit 33 and a processor power supply circuit 34.

[0023] The drive power supply circuit 33 generates DC power Vu, Vl of a predetermined voltage for operating the drive circuits 24a to 24c, 24d to 24f from the output of the low-voltage DC power supply 32, and supplies the generated power to the drive circuits 24a to 24c, 24d to 24f. The processor power supply circuit 34 generates DC power Vp of a predetermined voltage for operating the processor 21 from the output of the low-voltage DC power supply 32, and supplies the generated power to the processor 21.

[0024] In this embodiment, the voltages of the DC power output from the high-voltage DC power supply 30 and the low-voltage DC power supply 32 are different. That is, the voltage of the DC power output from the high-voltage DC power supply 30 is higher than the voltage of the DC power output from the low-voltage DC power supply 32. For example, the voltage of the DC power output from the high-voltage DC power supply 30 may be, for example, 200 to 400 [V], and the voltage of the DC power output from the low-voltage DC power supply 32 may be, for example, 12 to 24 [V].

[0025] The voltage of the DC power generated by the drive power supply circuit 33 and the voltage of the DC power generated by the processor power supply circuit 34 may be any voltage that corresponds to the circuit that each of them operates. For example, the drive circuits 24a-24c and 24d-24f are circuits for operating power switching elements (described in detail below) that constitute the inverter 10, which belongs to the high-voltage circuit. The drive power supply circuit 33 generates a voltage of, for example, about 12 to 18 V as a voltage that corresponds to the drive circuits 24a-24c and 24d-24f. Meanwhile, the processor 21 is an integrated circuit that performs various types of information processing. The processor power supply circuit 34 generates a voltage of, for example, 3.3 V or 5 V as a voltage that corresponds to the processor 21.

[0026] The processor power supply circuit 34 has a function of supplying the processor 21 with DC power Vp for operating the processor 21, as well as a function of monitoring the processor 21 and determining whether the power supply has stopped. Specifically, the processor 21 outputs a signal Watch indicating whether the processor 21 is operating normally to the processor power supply circuit 34. The signal Watch may be any signal that can determine whether the processor 21 is operating normally, and may be, for example, a signal indicating the result of periodically incrementing a variable value.

[0027] The processor power supply circuit 34 monitors whether the value indicated by the signal Watch is a predetermined value, and if the value is not the predetermined value, outputs a Reset signal to the processor 21. When the processor 21 receives the Reset signal, the processor 21 restarts. Therefore, if the processor 21 is operating abnormally, the processor 21 can be restarted, increasing the possibility of returning to normal operation. In this embodiment, the Reset signal is normally high level and is set to low level when the processor 21 is restarted.

[0028] The processor power supply circuit 34 also outputs a power supply state indication signal Vd that indicates whether the output of DC power Vp to the processor 21 is normal. In this embodiment, the power supply state indication signal Vd is a signal that is at a high level when the processor power supply circuit 34 is operating normally. If the processor power supply circuit 34 fails, the power supply state indication signal Vd is not output, i.e., is at a low level.

[0029] According to the above configuration, when the power supply state indication signal Vd is at a high level, power is being supplied from the processor power supply circuit 34 to the processor 21, and when the power supply state indication signal Vd is at a low level, it can be considered that the power supply from the processor power supply circuit 34 to the processor 21 has stopped.

[0030] In this embodiment, the Reset signal and the power supply state indication signal Vd are input to an AND gate 34a. The abnormality detection signal Sa, which is the output of the AND gate 34a, is input to the switching circuit 23. The Reset signal is high when the processor 21 is operating normally and low when the processor 21 is operating abnormally. The power supply state indication signal Vd is high when the processor power supply circuit 34 is operating normally and low when power supply to the processor 21 is stopped.

[0031] Therefore, the abnormality detection signal Sa output from the AND gate 34a goes low when the processor 21 operates abnormally or when the power supply to the processor 21 is stopped. The abnormality detection signal Sa output from the AND gate 34a goes high when the processor 21 is operating normally and the power supply to the processor 21 is not stopped.

[0032] The processor 21 is an IC circuit that controls each part in a predetermined procedure, and is configured by, for example, a microcomputer, a DSP (Digital Signal Processor), etc. As described above, the processor 21 is driven by DC power of a predetermined voltage generated by the processor power supply circuit 34.

[0033] The processor 21 performs current feedback control using a vector control method based on a target torque of the rotating electric machine 40 provided as a request signal via a CAN (Controller Area Network) or the like from another control device such as a vehicle control unit that controls the operation of the vehicle, and controls the rotating electric machine 40 via the inverter 10. Specifically, the processor 21 controls the upper-stage switching elements 11a to 11c and the lower-stage switching elements 11d to 11f of the inverter 10 via the switching circuit 23 and the drive circuits 24a to 24c and 24d to 24f.

[0034] The drive circuits 24a to 24c are circuits for switching on and off the upper-stage switching elements 11a to 11c, respectively. The drive circuits 24d to 24f are circuits for switching on and off the lower-stage switching elements 11d to 11f, respectively. The drive circuits 24a to 24c and 24d to 24f only need to be able to control the on and off of each switching element. When each switching element is an IGBT or FET, the control terminal is a gate terminal, so the drive circuits 24a to 24c and 24d to 24f generate drive signals to be applied to the gate terminal of each switching element. Here, these drive signals are called gate drive signals.

[0035] The rotating electric machine 40 is provided with a current sensor 41 and a rotation sensor 42. The actual current flowing through the coils of each phase of the rotating electric machine 40 is detected by the current sensor 41, and the processor 21 acquires the detection result. In addition, the magnetic pole position of the rotor of the rotating electric machine 40 at each point in time is detected by a rotation sensor 42, such as a resolver, and the processor 21 acquires the detection result. The processor 21 performs current feedback control using the detection results of the current sensor 41 and the rotation sensor 42. The processor 21 is configured with various functional units for current feedback control, and each functional unit is realized by cooperation between hardware such as a microcomputer or a DSP and software (program). Current feedback control is well known, so a detailed description will be omitted here. The above current feedback control is referred to as normal control.

[0036] The processor 21 specifies switching elements to be turned on or off for normal control, and instructs the drive circuits 24a to 24c, 24d to 24f corresponding to each switching element to turn on or off each switching element. The processor 21 outputs the instructions to the drive circuits 24a to 24c, 24d to 24f via the switching circuit 23 (the switching circuit 23 will be described later).

[0037] In response to the instruction, the drive circuits 24a to 24c and 24d to 24f use the power supplied from the drive power supply circuit 33 to generate gate drive signals that drive the upper-stage switching elements 11a to 11c and the lower-stage switching elements 11d to 11f, respectively.

[0038] If an undesirable event such as an overcurrent or overvoltage occurs in the vehicle, transmission, rotating electric machine 40, inverter 10, etc., and if such an event occurs in a rotating electric machine drive device including at least the inverter 10, the processor 21 performs fail-safe control that differs from normal control to restrict the operation of the rotating electric machine 40. The processor 21 executes fail-safe control when it directly acquires detection information, or in response to a fail-safe control request from another control device such as a vehicle control unit, to cause the inverter 10 to perform a fail-safe operation.

[0039] The fail-safe control is realized by shutdown control and active short circuit control. The shutdown control is a control that turns off all of the upper-stage switching elements 11a to 11c and the lower-stage switching elements 11d to 11f. The active short circuit control is a control that turns on one stage of the upper-stage switching elements 11a to 11c and the lower-stage switching elements 11d to 11f and turns off the other stage.

[0040] During shutdown control, all switching elements of the inverter 10 are turned off. At this time, the rotor of the rotating electric machine 40 continues to rotate due to inertia, generating a large back electromotive force between the motor lines. The voltage of the back electromotive force between the motor lines increases as the rotational speed of the rotating electric machine 40 increases, and when the rotating electric machine 40 is rotating at high speed, the voltage of the back electromotive force between the motor lines becomes much larger than the DC link voltage Vdc. The power generated by the rotation of the rotating electric machine 40 is rectified via diodes 13a to 13f and passes through the closed contactor 15 to charge the high-voltage DC power supply 30.

[0041] FIG. 2 is a diagram showing an example of the battery current Ib (the current flowing through the high-voltage DC power supply 30) and the DC link voltage Vdc when shutdown control is being performed. In each graph, the horizontal axis represents time t, with the upper graph showing the change over time in the battery current Ib and the lower graph showing the change over time in the DC link voltage Vdc. When shutdown control is initiated at time tsd, as shown in the upper graph, the absolute value of the battery current Ib increases significantly. If this battery current Ib exceeds the rated current of the high-voltage DC power supply 30, this may cause wear and tear on or damage to the high-voltage DC power supply 30. On the other hand, increasing the rated value of the high-voltage DC power supply 30 so that it can withstand a large battery current Ib may result in an increase in size and cost.

[0042] After the shutdown control starts, when the contactor 15 is opened at time to open, the current flow into the high-voltage DC power supply 30 is cut off. In this case, as shown in the upper graph of FIG. 2, the battery current Ib becomes zero. The current whose flow into the high-voltage DC power supply 30 is cut off charges the smoothing capacitor 14, causing the DC link voltage Vdc to increase. That is, as shown in the lower graph of FIG. 2, when the contactor 15 opens at time to open, the DC link voltage Vdc rises sharply. If the DC link voltage Vdc exceeds the rated voltage (absolute maximum rating) of the inverter 10 (each switching element) or the smoothing capacitor 14, these elements may be damaged. Increasing these rated values ​​to allow for a higher voltage may result in an increase in size and cost.

[0043] Therefore, when an event such as an overcurrent or an overvoltage occurs in a rotary electric machine drive device equipped with the inverter 10, it is desirable to execute fail-safe control while suppressing an excessive increase in the battery current Ib and the DC link voltage Vdc when charging the high-voltage DC power supply 30. In view of this background, in this embodiment, the processor 21 selects a control method according to the rotation speed of the rotary electric machine 40.

[0044] Specifically, the processor 21 selectively executes shutdown control and active short circuit control. That is, the processor 21 controls the upper-stage switching elements 11a to 11c and the lower-stage switching elements 11d to 11f by issuing instructions to the drive circuits 24a to 24c and 24d to 24f via the switching circuit 23, thereby causing the inverter 10 to selectively perform a shutdown operation or an active short circuit operation.

[0045] As described above, shutdown control is control that turns off all switching elements of the inverter 10. Therefore, when shutdown control is selected, the processor 21 instructs the drive circuits 24a to 24c and 24d to 24f to turn off each switching element. As a result, the drive circuits 24a to 24c do not output gate drive signals to the upper-stage switching elements 11a to 11c, turning off all of the upper-stage switching elements 11a to 11c. Furthermore, the drive circuits 24d to 24f do not output gate drive signals to the lower-stage switching elements 11d to 11f, turning off all of the lower-stage switching elements 11d to 11f.

[0046] Active short circuit control is a control for circulating current between the rotating electric machine 40 and the inverter 10. Specifically, active short circuit control turns on the upper-side switching elements 11a to 11c of all arms of the multiple phases and turns off the lower-side switching elements 11d to 11f of all arms of the multiple phases, or turns off the upper-side switching elements 11a to 11c of all arms of the multiple phases and turns on the lower-side switching elements 11d to 11f of all arms of the multiple phases. That is, in active short circuit control, one of the upper side or the lower side is turned on and the other side is turned off. In the present embodiment, hereinafter, an example in which the upper side is turned off and the lower side is turned on is assumed.

[0047] In this embodiment, when active short circuit control is selected, the processor 21 instructs the drive circuits 24a to 24c to turn off the upper-stage switching elements 11a to 11c via the switching circuit 23. The processor 21 also instructs the drive circuits 24d to 24f to turn on the lower-stage switching elements 11d to 11f via the switching circuit 23.

[0048] As a result, the drive circuits 24a to 24c do not output gate drive signals to the upper-stage switching elements 11a to 11c, turning all of the upper-stage switching elements 11a to 11c off, and the drive circuits 24d to 24f output gate drive signals to the lower-stage switching elements 11d to 11f, turning all of the lower-stage switching elements 11d to 11f on.

[0049] In this embodiment, the processor 21 selects a control method depending on at least the rotational speed of the rotating electric machine 40. Specifically, the processor 21 selects active short circuit control in a high rotational speed region where the rotational speed ω of the rotating electric machine 40 is equal to or greater than a predetermined switching rotational speed ωsw. Furthermore, the processor 21 selects shutdown control in a low rotational speed region where the rotational speed ω of the rotating electric machine 40 is lower than the switching rotational speed ωsw. As described above, in this embodiment, the processor 21 switches the control method depending on whether the rotational speed ω of the rotating electric machine 40 is equal to or greater than the switching rotational speed ωsw. Note that the switching rotational speed ωsw may be a fixed value or may be a variable value. As the latter, for example, the switching rotational speed ωsw when switching from shutdown control to active short circuit control may be different from the switching rotational speed ωsw when switching from active short circuit control to shutdown control. More specifically, a configuration in which the latter switching rotational speed ωsw is smaller than the former switching rotational speed ωsw may be employed.

[0050] As described above, the processor 21 can execute fail-safe control. However, if the power supply to the processor 21 is stopped, the processor 21 will be unable to select a control method or issue instructions to the drive circuits 24a to 24c and 24d to 24f. For example, the power supply to the processor 21 may be stopped due to a failure of the processor power supply circuit 34, a break in the wiring that supplies power from the low-voltage DC power supply 32 to the processor power supply circuit 34, or the like.

[0051] In such a case, the processor 21 will not operate, making it impossible to select a control method according to the rotation speed of the rotating electric machine 40. Therefore, in this embodiment, even if the power supply to the processor 21 is stopped, a configuration is provided for executing control in an abnormal state using a control method according to the rotation speed of the rotating electric machine 40 immediately before the power supply was stopped.

[0052] Specifically, the control circuit 20 includes a buffering circuit 22 and a switching circuit 23. The buffering circuit 22 is a circuit that buffers information indicating whether the control corresponding to the current rotation speed of the rotating electric machine 40 is shutdown control or active short circuit control. The switching circuit 23 is a circuit that causes the inverter to perform the control indicated by the information buffered in the buffering circuit 22 when the power supply to the processor 21 is stopped.

[0053] FIG. 3 is a diagram illustrating an example of the buffering circuit 22 and the switching circuit 23. The processor 21 determines, based on the rotational speed of the rotating electric machine 40, whether the control to be executed at that rotational speed is shutdown control or active short-circuit control. The processor 21 then outputs information indicating the determination result, i.e., a signal indicating whether the control corresponding to the rotational speed is shutdown control or active short-circuit control, from a predetermined output terminal T1. Specifically, the predetermined output terminal T1 outputs a high-level or low-level voltage to indicate whether the control executed by the inverter 10 is shutdown control or active short-circuit control. In this embodiment, if the control corresponding to the rotational speed of the rotating electric machine 40 is shutdown control, a low-level signal is output from the output terminal T1. If the control corresponding to the rotational speed of the rotating electric machine 40 is active short-circuit control, a high-level signal is output from the output terminal T1. In this specification, the signal output from the output terminal T1 is referred to as a control mode instruction signal Sp. In normal control in which current feedback control using the vector control method is executed, shutdown control and active short circuit control are not executed, but in preparation for a state transition, processor 21 constantly determines whether the control corresponding to the rotation speed of rotating electric machine 40 is shutdown control or active short circuit control. Furthermore, processor 21 constantly outputs, from output terminal T1, information indicating whether the control corresponding to the rotation speed of rotating electric machine 40 is shutdown control or active short circuit control.

[0054] The control mode instruction signal Sp is input to the buffering circuit 22. In this embodiment, the buffering circuit 22 includes a latch circuit that latches the voltage (control mode instruction signal Sp) output from a predetermined output terminal T1. In the example shown in FIG. 3, the latch circuit is a D latch circuit. The control mode instruction signal Sp is input to an input terminal D of the buffering circuit 22. A predetermined clock signal CLK is input from the processor 21 to a clock input terminal CL of the buffering circuit 22.

[0055] An output terminal Q of the buffering circuit 22 is input to one of the input terminals of selector circuits 23d, 23e, and 23f, which will be described later. In the example shown in Fig. 3, the buffering circuit 22 is a D-latch circuit, so that the control mode instruction signal Sp input to the input terminal D is latched in synchronization with the clock signal CLK and output from the output terminal Q. In this embodiment, the D-latch circuit latches the signal input to the input terminal D in synchronization with the rising edge of the clock signal CLK.

[0056] Fig. 4 is a diagram showing the operation of the D latch circuit. In this embodiment, the D latch circuit latches in synchronization with the rising edge of the clock signal CLK, so that, as shown in Fig. 4, at timings other than the rising edge of the clock signal CLK, the output from the output terminal Q remains unchanged regardless of whether the control mode instruction signal Sp input to the input terminal D is at low level L or high level H.

[0057] On the other hand, if the control mode instruction signal Sp input to the input terminal D is at low level L at the rising timing of the clock signal CLK, the output from the output terminal Q will be at low level L. Also, if the control mode instruction signal Sp input to the input terminal D is at high level H at the rising timing of the clock signal CLK, the output from the output terminal Q will be at high level H.

[0058] The control mode instruction signal Sp is a signal that indicates whether the control method that the processor 21 has identified as the control to be executed in accordance with the rotational speed of the rotating electric machine 40 is shutdown control or active short circuit control. When the control mode instruction signal Sp changes, the buffering circuit 22 latches it in synchronization with the rising edge of the clock signal CLK immediately after the control mode instruction signal Sp changes. Therefore, the buffering circuit 22 buffers information that indicates the control method identified by the processor 21.

[0059] The switching circuit 23 is interposed between the processor 21 and the drive circuits 24a to 24c, 24d to 24f. In the example shown in Fig. 3, the switching circuit 23 includes a plurality of selector circuits 23a to 23c, 23d to 23f. The selector circuits 23a to 23c, 23d to 23f are two-input, one-output selectors that select and output one of two inputs in response to a control signal.

[0060] In this embodiment, one input terminal I1 of each of the selector circuits 23a to 23c, 23d to 23f is electrically connected to the processor 21. A first signal Sc for controlling the inverter 10 is output from the processor 21 and input to the input terminal I1. The first signal Sc is a signal for issuing instructions to each of the drive circuits 24a to 24c, 24d to 24f during normal control and fail-safe control.

[0061] The other input terminals I2 of the selector circuits 23a to 23c are fixed to a low level (Low). Fixing to a low level can be achieved, for example, by grounding. The other input terminals I2 of the selector circuits 23d to 23f are electrically connected to the output terminal Q of the buffering circuit 22. Therefore, the other input terminals I2 of the selector circuits 23d to 23f receive a control mode instruction signal Sp (second signal) output from the buffering circuit 22 and indicating the buffered information.

[0062] The control signal input to the selector circuits 23a to 23c and 23d to 23f is the abnormality detection signal Sa. As described above, the abnormality detection signal Sa goes low in an abnormal state (when the processor 21 operates abnormally or when the power supply to the processor 21 is stopped), and goes high in a normal state (when the processor 21 operates normally and the power supply to the processor 21 is not stopped).

[0063] In the selector circuits 23a to 23c and 23d to 23f, when the control signal is at a high level, the signal at the input terminal I1 is selected and output from the output terminal O. In the selector circuits 23a to 23c and 23d to 23f, when the control signal is at a low level, the signal at the input terminal I2 is selected and output from the output terminal O. In this embodiment, the output terminals O of the selector circuits 23a to 23c are electrically connected to the drive circuits 24a to 24c.

[0064] As described above, the abnormality detection signal Sa as a control signal is at a high level in the normal state, so that in the normal state, the signal at the input terminal I1 is selected and an instruction to perform normal control or fail-safe control output from the processor 21 is input to the drive circuits 24a to 24c, 24d to 24f. Therefore, in the normal state, the inverter 10 is subjected to normal control or fail-safe control.

[0065] On the other hand, the abnormality detection signal Sa serving as a control signal is at a low level in an abnormal state, and therefore the signal at the input terminal I2 is selected in the selector circuits 23a to 23c and 23d to 23f. The input terminal I2 of the selector circuits 23a to 23c, which are electrically connected to the drive circuits 24a to 24c corresponding to the upper-stage switching elements 11a to 11c, is fixed at a low level. In other words, no signal is input from the buffering circuit 22 to the input terminal I2 of the selector circuits 23a to 23c. Therefore, the buffering circuit 22 according to this embodiment does not supply the control mode instruction signal Sp (second signal) to the drive circuits 24a to 24c corresponding to the upper-stage switching elements 11a to 11c.

[0066] In an abnormal state, the selector circuits 23a to 23c input low-level signals to the drive circuits 24a to 24c. In this case, the drive circuits 24a to 24c do not output gate drive signals to the upper-stage switching elements 11a to 11c, and turn off the upper-stage switching elements 11a to 11c.

[0067] The latched control mode instruction signal Sp is input to the input terminals I2 of the selector circuits 23d to 23f, which are electrically connected to the drive circuits 24d to 24f corresponding to the lower-stage switching elements 11d to 11f. That is, a signal from the buffering circuit 22 is input to the input terminals I2 of the selector circuits 23d to 23f. Therefore, the buffering circuit 22 according to this embodiment supplies the control mode instruction signal Sp (second signal) to the drive circuits 24d to 24f corresponding to the lower-stage switching elements 11d to 11f.

[0068] In an abnormal state, the selector circuits 23d-23f input the latched control mode instruction signal Sp to the drive circuits 24d-24f. In this case, the selector circuits 23d-23f input a high-level or low-level signal indicated by the control mode instruction signal Sp to the drive circuits 24d-24f. The drive circuits 24d-24f output or do not output gate drive signals to the lower-stage switching elements 11d-11f in accordance with the control mode instruction signal Sp, thereby turning the lower-stage switching elements 11d-11f on or off.

[0069] If the control according to the rotation speed of the rotating electrical machine 40 during normal control or fail-safe control immediately before the abnormal state occurred was shutdown control, the control mode instruction signal Sp is a low-level signal. When this low-level signal is input to the drive circuits 24d-24f, the drive circuits 24d-24f do not output gate drive signals to the lower-stage switching elements 11d-11f, and turn off the lower-stage switching elements 11d-11f. As a result, all of the upper-stage switching elements 11a-11c and 11d-11f are turned off, realizing a state identical to that in which shutdown control is being performed.

[0070] If the control according to the rotational speed of the rotating electrical machine 40 during normal control or fail-safe control immediately before the abnormal state occurred was active short-circuit control, the control mode instruction signal Sp is a high-level signal. When this high-level signal is input to the drive circuits 24d to 24f, the drive circuits 24d to 24f output gate drive signals to the lower-stage switching elements 11d to 11f, turning on the lower-stage switching elements 11d to 11f. As a result, the upper-stage switching elements 11a to 11c are turned off and the lower-stage switching elements 11d to 11f are turned on, realizing a state identical to that in which active short-circuit control is being performed.

[0071] In this embodiment, the buffering circuit 22 and the switching circuit 23 operate on the basis of power supplied from a power supply circuit different from the processor power supply circuit 34, for example, a circuit that operates by receiving power from the drive power supply circuit 33 or a low-voltage DC power supply. Therefore, even if power is not supplied to the processor 21 due to a failure of the processor power supply circuit 34 or the like and the processor 21 is not operating, the information latched in the buffering circuit 22 is maintained, and the switching circuit 23 operates on the basis of the latched information.

[0072] According to the above configuration, the control method selected by the processor 21 in accordance with the rotation speed of the rotating electric machine 40 is buffered, so that even if the power supply to the processor 21 is stopped, the inverter 10 can be controlled by the control method selected immediately before the power supply to the processor 21 is stopped. Therefore, it is possible to execute fail-safe control with a simple configuration without restoring the power supply to the processor 21 by a backup power supply or the like.

[0073] The control method selected after the power supply to the processor 21 is stopped is the control method selected by the processor 21 in accordance with the rotational speed ω of the rotating electric machine 40 immediately before the power supply is stopped. Therefore, immediately after the power supply is stopped, the control method in accordance with the rotational speed ω of the rotating electric machine 40 immediately before the power supply is stopped is selected and executed. It is estimated that the rotational speed ω of the rotating electric machine 40 does not fluctuate significantly between immediately before and immediately after the power supply is stopped. Therefore, according to this embodiment, it is possible to increase the likelihood that an appropriate control method in accordance with the rotational speed ω of the rotating electric machine 40 will be selected even immediately after the power supply is stopped.

[0074] Furthermore, in the above configuration, active short circuit control is selected when the rotational speed ω of the rotating electric machine 40 is equal to or greater than the switching rotational speed ωsw, and shutdown control is selected when the rotational speed ω is less than the switching rotational speed ωsw. Therefore, if the rotational speed ω of the rotating electric machine 40 immediately before the power supply to the processor 21 is stopped is equal to or greater than the switching rotational speed ωsw, active short circuit control is executed immediately after the power supply is stopped. This configuration can reduce the possibility that active short circuit control will be selected when the rotational speed ω of the rotating electric machine 40 is a low rotational speed lower than the switching rotational speed ωsw.

[0075] When active short circuit control is performed at low rotational speeds, an inrush current occurs in the inverter 10. However, when the rotational speed ω of the rotating electric machine 40 is low, the inrush current is larger than when the rotational speed ω is high. For this reason, when active short circuit control is performed at a low rotational speed where the rotational speed ω of the rotating electric machine 40 is lower than the switching rotational speed ωsw, the inrush current may become excessively large. In this embodiment, shutdown control is selected and active short circuit control is not selected at a low rotational speed where the rotational speed ω of the rotating electric machine 40 is lower than the switching rotational speed ωsw, so the possibility of the inrush current accompanying active short circuit control becoming excessively large can be reduced.

[0076] Furthermore, when the inrush current becomes large, a braking force is generated in the vehicle as a result, but since there is a rotational speed at which the inrush current is maximum at low rotational speeds, there is also a rotational speed at which the braking force is maximum at low rotational speeds. In this embodiment, at low rotational speeds where the rotational speed ω of the rotating electrical machine 40 is lower than the switching rotational speed ωsw, the shutdown control is selected and the active short circuit control is not selected, so it is possible to reduce the possibility of excessive braking (sudden braking) occurring due to the active short circuit control.

[0077] Furthermore, according to this embodiment, if the rotation speed ω of the rotating electrical machine 40 immediately before the power supply to the processor 21 is stopped is lower than the switching rotation speed ωsw, the shutdown control is executed immediately after the power supply is stopped. This configuration can reduce the possibility that the shutdown control will be selected when the rotation speed ω of the rotating electrical machine 40 is a high rotation speed that is equal to or higher than the switching rotation speed ωsw.

[0078] When shutdown control is executed, a back electromotive force is generated by the magnet of the rotor provided in the rotating electric machine 40, and this back electromotive force becomes larger when the rotation speed ω of the rotating electric machine 40 is high. For this reason, when shutdown control is executed at a high rotation speed, there is a possibility that the withstand voltage of the inverter 10 will be exceeded. However, in this embodiment, when the rotation speed ω of the rotating electric machine 40 is a high rotation speed equal to or higher than the switching rotation speed ωsw, active short circuit control is selected and shutdown control is not selected, so it is possible to reduce the possibility that the back electromotive force caused by shutdown control will exceed the withstand voltage of the inverter 10.

[0079] Furthermore, in this embodiment, the control method selected immediately before the power supply to the processor 21 is stopped is buffered, and the buffered control method is executed immediately after the power supply is stopped. Therefore, the control method corresponding to the rotational speed ω of the rotating electric machine 40 immediately before the power supply is stopped continues to be selected. On the other hand, when the power supply is stopped, some kind of abnormality has occurred, so the vehicle is usually stopped promptly. That is, the rotational speed ω of the rotating electric machine 40 usually gradually decreases.

[0080] Therefore, because the rotational speed ω of the rotating electric machine 40 was high immediately before the power supply was stopped, after active short circuit control was selected, the rotational speed ω gradually decreased and may become smaller than the switching rotational speed ωsw. However, the excessive inrush current and sudden braking associated with active short circuit control are problems that may occur mainly when active short circuit control is started, and are unlikely to occur if active short circuit control is continuously performed. In this way, even if active short circuit control is selected immediately after the power supply is stopped and then continues without selecting a control method according to the rotational speed ω, the problems of excessive inrush current and sudden braking will not occur.

[0081] Furthermore, if the rotation speed ω of the rotating electric machine 40 immediately before the power supply is stopped is low, the shutdown control is selected immediately after the power supply is stopped, but it is not expected that the rotation speed ω of the rotating electric machine 40 will increase thereafter. Therefore, performing the shutdown control at a high rotation speed will not cause a problem such as the generation of a back electromotive force that exceeds the withstand voltage of the inverter 10.

[0082] Furthermore, in this embodiment, since a control mode instruction signal Sp indicating the selected control mode is output from the processor 21, the control mode can be maintained simply by latching the control mode instruction signal Sp in a latch circuit. Therefore, with a simple configuration, it is possible to take measures against a stop of power supply to the processor 21.

[0083] Furthermore, in this embodiment, the switching circuit 23 switches between instructions given to the drive circuits 24a to 24c and 24d to 24f when power is being supplied to the processor 21 and when power supply is stopped. Therefore, with a simple configuration, it is possible to give instructions to the drive circuits 24a to 24c and 24d to 24f depending on whether power is being supplied or not.

[0084] Furthermore, in this embodiment, the control mode instruction signal Sp is supplied to either the drive circuits 24a-24c corresponding to the upper-stage switching elements 11a-11c or the drive circuits 24d-24f corresponding to the lower-stage switching elements 11d-11f, while the control mode instruction signal Sp is not supplied to the other and is fixed at a low level. That is, the operation of either the drive circuits 24a-24c or the drive circuits 24d-24f is controlled by the control mode instruction signal Sp, while the operation of the other is fixedly turned off. With this configuration, it is possible to select between shutdown control and active short circuit control by controlling only one of the upper-stage switching elements 11a-11c or the lower-stage switching elements 11d-11f. Therefore, a circuit that selects a control mode can be provided with a simple configuration.

[0085] (2) Example of operation: Next, an example of the operation of the rotating electric machine control device described above will be described. In the following examples, FIGS. 5 and 6 show examples in which power supply to the processor 21 is stopped during fail-safe control, and FIGS. 7 and 8 show examples in which power supply to the processor 21 is stopped during normal control. FIG. 5 is a timing chart showing an example of the control state and time-series changes in signals of each part of the circuit. In the example shown in FIG. 5, it is assumed that the operation of the rotating electric machine control device starts at time t1 and normal control is performed until time t2. It is also assumed that after time t2, an undesirable event such as an overcurrent or overvoltage occurs in the rotating electric machine drive device, and that fail-safe control is performed from time t2 to time t6. It is also assumed that power supply to the processor 21 is stopped at time t6.

[0086] 5, the top row indicates whether the control being performed by the processor 21 is normal control or fail-safe control (F / S control). That is, in the top row, 1 indicates a period of normal control, and 0 indicates a period of fail-safe control. The second and third rows indicate whether the control selected by the processor 21 as control according to the rotational speed of the rotating electric machine 40 is shutdown control or active short circuit control. In these timing charts, the period during which the control shown on the left is selected is indicated by 1, and the period during which the control is not selected is indicated by 0.

[0087] The fourth to seventh rows of Fig. 5 show examples of time-series changes in the abnormality detection signal Sa, the control mode instruction signal Sp, the output signal of the output terminal Q, and the clock signal CLK. The eighth row of Fig. 5 shows which of the signals from the input terminals I1 and I2 is the signal that forms the basis of the outputs of the selector circuits 23a to 23c and 23d to 23f.

[0088] Between time t1 and time t2, the processor power supply circuit 34 operates normally, and the power supply state indication signal Vd is at a high level. Furthermore, because the processor 21 also operates normally, the Reset signal is at a high level, and no operation to set it to a low level for restarting is performed. As a result, between time t1 and time t2, the abnormality detection signal Sa remains at a high level. Therefore, the control signals of the selector circuits 23a-23c and 23d-23f become a high level, and the input signal to the input terminal I1 is output from the output terminal O.

[0089] During the period from time t1 to time t2 when normal control is being performed, the processor 21 outputs a control mode instruction signal Sp based on the determination made by the processor 21. However, FIG. 5 illustrates an example in which the control mode instruction signal Sp is at a low level during the period from time t1 to time t2. That is, FIG. 5 illustrates an example in which the control according to the rotational speed of the rotating electric machine 40 during the period from time t1 to time t2 is shutdown control. In this case, the processor 21 does not output the control mode instruction signal Sp, but rather keeps it at a low level. Therefore, during the period of normal control illustrated in FIG. 5, even if the buffering circuit 22 latches at the rising edge of the clock signal CLK, the latched level is a low level, and the output of the output terminal Q is also maintained at a low level.

[0090] Fail-safe control is performed during the period from time t2 to time t6. In the example shown in Fig. 5, active short circuit (ASC) control is performed from time t2 to time t4. Therefore, the processor 21 outputs a high-level signal, which is a control mode instruction signal Sp, indicating that active short circuit control has been selected during the period from time t2 to time t4.

[0091] In this state, when the buffering circuit 22 performs latching at time t3, which is the rising edge of the clock signal CLK, the high-level control mode instruction signal Sp is latched, and the output from the output terminal Q becomes high. However, even though fail-safe control is being performed, the processor power supply circuit 34 and the processor 21 operate normally from time t2 to time t6. Therefore, the power supply state instruction signal Vd becomes high, the Reset signal becomes high, and the abnormality detection signal Sa becomes high. As a result, the control signals of the selector circuits 23a to 23c and 23d to 23f become high, and the input signal to the input terminal I1 is output from the output terminal O. Therefore, the output content of the buffering circuit 22 does not affect the control of the drive circuits 24a to 24c and 24d to 24f.

[0092] 5, shutdown (SDN) control is performed from time t4 to time t6. Therefore, during the period from time t4 to time t6, the processor 21 outputs a low-level signal that is a control mode instruction signal Sp indicating that shutdown control has been selected.

[0093] In this state, when the buffering circuit 22 latches at time t5, which is the rising edge of the clock signal CLK, the low-level control mode instruction signal Sp is latched, and the output from the output terminal Q becomes low. However, the processor power supply circuit 34 and the processor 21 are still operating normally. Therefore, the abnormality detection signal Sa becomes high, and the selector circuits 23a to 23c, 23d to 23f select the input signal to the input terminal I1 and output it from the output terminal O. Therefore, the output content of the buffering circuit 22 does not affect the control of the drive circuits 24a to 24c, 24d to 24f.

[0094] 5, it is assumed that the power supply to the processor 21 is stopped at time t6. In this case, the clock signal CLK output from the processor 21 is stopped. Furthermore, the power supply state indication signal Vd output from the processor 21 goes low, and the abnormality detection signal Sa goes low. As a result, the control signals of the selector circuits 23a to 23c and 23d to 23f go low, and the input signal to the input terminal I2 is output from the output terminal O. Therefore, the signals output from the output terminal O of the selector circuits 23a to 23c go low.

[0095] Furthermore, the information latched in the buffering circuit 22 immediately after time t6 is the information latched immediately before time t6, and is at a low level. Therefore, the signals output from the output terminals O of the selector circuits 23d to 23f are at a low level. Because the clock signal CLK is stopped, no new latching is performed in the buffering circuit 22. As a result, the output signals of all of the selector circuits 23a to 23c and 23d to 23f are at a low level. Therefore, the signals input to the drive circuits 24a to 24c and 24d to 24f are at a low level, and the drive circuits 24a to 24c and 24d to 24f turn off all of the upper-stage switching elements 11a to 11c and the lower-stage switching elements 11d to 11f. As a result, shutdown control is performed in the inverter 10, and the control method selected immediately before time t6 is continued.

[0096] Figure 6 shows an example in which different control methods are selected from time t2 to time t6 shown in Figure 5. Specifically, it is assumed that shutdown control is selected from time t2 to time t4, and active short circuit control is selected from time t4 to time t6. In this example, the operation from time t1 to time t2 is the same as that shown in Figure 5.

[0097] 6, shutdown (SDN) control is performed from time t2 to time t4. Therefore, during the period from time t2 to time t4, processor 21 outputs a low-level signal that is a control mode instruction signal Sp indicating that shutdown control has been selected.

[0098] In this state, when buffering circuit 22 performs latching at time t3, which is the rising edge of clock signal CLK, low-level control mode instruction signal Sp is latched, and the output from output terminal Q becomes low level. During the period from time t2 to time t6, processor power supply circuit 34 and processor 21 are operating normally, so abnormality detection signal Sa becomes high level. As a result, the input signal to input terminal I1 is output from output terminal O, and the output content of buffering circuit 22 does not affect the control of drive circuits 24a to 24c, 24d to 24f.

[0099] 6, active short circuit (ASC) control is performed from time t4 to time t6. Therefore, the processor 21 outputs a high-level signal, which is a control mode instruction signal Sp, indicating that active short circuit control is selected, during the period from time t4 to time t6.

[0100] In this state, when buffering circuit 22 latches at time t5, which is the rising edge of clock signal CLK, high-level control mode instruction signal Sp is latched, and the output from output terminal Q becomes high level. However, since processor power supply circuit 34 and processor 21 are still operating normally, abnormality detection signal Sa becomes high level. As a result, the input signal to input terminal I1 is output from output terminal O, and the output content of buffering circuit 22 does not affect the control of drive circuits 24a to 24c, 24d to 24f.

[0101] 6, it is assumed that the power supply to the processor 21 is stopped at time t6. In this case, the clock signal CLK output from the processor 21 is stopped. Furthermore, the power supply state indication signal Vd output from the processor 21 goes low, and the abnormality detection signal Sa goes low. As a result, the control signals of the selector circuits 23a to 23c and 23d to 23f go low, and the input signal to the input terminal I2 is output from the output terminal O. Therefore, the signals output from the output terminal O of the selector circuits 23a to 23c go low.

[0102] Furthermore, the information latched in the buffering circuit 22 immediately after time t6 is the information latched immediately before time t6, and is at high level. Therefore, the signals output from the output terminals O of the selector circuits 23d to 23f are at high level. Since the clock signal CLK is stopped, no new latching is performed in the buffering circuit 22.

[0103] As a result of the above, the output signals of the selector circuits 23a to 23c become low level. Therefore, the signals input to the drive circuits 24a to 24c are low level, and the drive circuits 24a to 24c turn off the upper-stage switching elements 11a to 11c. Meanwhile, the output signals of the selector circuits 23d to 23f become high level. Therefore, the signals input to the drive circuits 24d to 24f are high level, and the drive circuits 24a to 24c turn on the lower-stage switching elements 11d to 11f. As a result, the active short circuit control is performed in the inverter 10, and the control method selected immediately before time t6 is continued.

[0104] Fig. 7 shows an example in which normal control is performed from time t1 to time t6 shown in Fig. 5, but the power supply to the processor 21 is stopped at time t6. That is, in Fig. 7, unlike Fig. 5, it is assumed that the power supply to the processor 21 is stopped without performing fail-safe control. Also, in Fig. 7, it is assumed that the processor 21 determines that the control according to the rotational speed of the rotating electric machine 40 is active short circuit control from time t2 to time t4, and determines that it is shutdown control from time t1 to time t2 and from time t4 to time t6.

[0105] During the period from time t1 to time t6, the processor power supply circuit 34 operates normally. Therefore, during the period from time t1 to time t6, the abnormality detection signal Sa is maintained at a high level. As a result, the control signals of the selector circuits 23a to 23c and 23d to 23f become a high level, and the input signal to the input terminal I1 is output from the output terminal O.

[0106] During the period from time t1 to time t2, the processor 21 determines that the control according to the rotation speed of the rotating electrical machine 40 is shutdown control, and outputs a low-level control mode instruction signal Sp. Therefore, even if the buffering circuit 22 performs latching at the rising edge of the clock signal CLK, the latched level is low, and the output of the output terminal Q is also maintained at low level.

[0107] During the period from time t2 to time t4, the processor 21 determines that the control according to the rotational speed of the rotating electrical machine 40 is active short-circuit control, and outputs a high-level control mode instruction signal Sp. Therefore, when the buffering circuit 22 performs latching at time t3, which is the rising edge of the clock signal CLK, the high-level control mode instruction signal Sp is latched, and the output from the output terminal Q becomes high. However, in the example shown in FIG. 7, during the period from time t2 to time t6, the processor power supply circuit 34 and the processor 21 operate normally, and the abnormality detection signal Sa is high. As a result, an input signal is output from the output terminal O of the selector circuits 23a to 23c, 23d to 23f to the input terminal I1, and the output content of the buffering circuit 22 does not affect the control of the drive circuits 24a to 24c, 24d to 24f.

[0108] During the period from time t4 to time t6, the processor 21 determines that the control according to the rotational speed of the rotating electrical machine 40 is shutdown control, and outputs a low-level control mode instruction signal Sp. Therefore, when the buffering circuit 22 performs latching at time t5, which is the rising edge of the clock signal CLK, the low-level control mode instruction signal Sp is latched, and the output from the output terminal Q becomes low. However, even here, the processor power supply circuit 34 and the processor 21 are operating normally. Therefore, during the period up to time t6, the output content of the buffering circuit 22 does not affect the control of the drive circuits 24a to 24c, 24d to 24f.

[0109] 7, it is assumed that the power supply to the processor 21 is stopped at time t6. In this case, the clock signal CLK output from the processor 21 is stopped. Furthermore, the power supply state indication signal Vd output from the processor 21 goes low, and the abnormality detection signal Sa goes low. As a result, the control signals of the selector circuits 23a to 23c and 23d to 23f go low, and the input signal to the input terminal I2 is output from the output terminal O. Therefore, the signals output from the output terminal O of the selector circuits 23a to 23c go low.

[0110] Furthermore, the information latched in the buffering circuit 22 immediately after time t6 is the information latched immediately before time t6, and is at low level. Therefore, the signals output from the output terminals O of the selector circuits 23d to 23f are at low level. Since the clock signal CLK is stopped, no new latching is performed in the buffering circuit 22.

[0111] As a result, the output signals of all of the selector circuits 23a-23c and 23d-23f go low. Therefore, the signals input to the drive circuits 24a-24c and 24d-24f are low, and the drive circuits 24a-24c and 24d-24f turn off all of the upper-stage switching elements 11a-11c and lower-stage switching elements 11d-11f. As a result, shutdown control is performed in the inverter 10, and the control method selected immediately before time t6 continues.

[0112] Fig. 8 shows an example in which normal control is performed from time t1 to time t6 shown in Fig. 6, but the power supply to the processor 21 is stopped at time t6. That is, in Fig. 8, unlike Fig. 6, it is assumed that the power supply to the processor 21 is stopped without performing fail-safe control. Also, in Fig. 8, it is assumed that the processor 21 determines that the control according to the rotational speed of the rotating electric machine 40 is shutdown control from time t1 to time t4, and determines that it is active short circuit control from time t4 to time t6.

[0113] During the period from time t1 to time t6, the processor power supply circuit 34 operates normally. Therefore, during the period from time t1 to time t6, the abnormality detection signal Sa is maintained at a high level. As a result, the control signals of the selector circuits 23a to 23c and 23d to 23f become a high level, and the input signal to the input terminal I1 is output from the output terminal O.

[0114] During the period from time t1 to time t4, the processor 21 determines that the control according to the rotational speed of the rotating electrical machine 40 is shutdown control, and outputs a low-level control mode instruction signal Sp. Therefore, even if the buffering circuit 22 performs latching at the rising edge of the clock signal CLK, the latched level is low, and the output from the output terminal Q is also maintained at low level. However, in the example shown in FIG. 8, during the period from time t1 to time t4, the processor power supply circuit 34 and the processor 21 are operating normally, and the abnormality detection signal Sa is high. As a result, an input signal is output from the output terminal O of the selector circuits 23a to 23c, 23d to 23f to the input terminal I1, and the output content of the buffering circuit 22 does not affect the control of the drive circuits 24a to 24c, 24d to 24f.

[0115] During the period from time t4 to time t6, the processor 21 determines that the control according to the rotational speed of the rotating electrical machine 40 is active short-circuit control, and outputs a high-level control mode instruction signal Sp. Therefore, when the buffering circuit 22 performs latching at time t5, which is the rising edge of the clock signal CLK, the high-level control mode instruction signal Sp is latched, and the output from the output terminal Q becomes high. However, in the example shown in FIG. 8, during the period from time t4 to time t6, the processor power supply circuit 34 and the processor 21 are operating normally, and the abnormality detection signal Sa is high. As a result, an input signal is output from the output terminal O of the selector circuits 23a to 23c, 23d to 23f to the input terminal I1, and the output content of the buffering circuit 22 does not affect the control of the drive circuits 24a to 24c, 24d to 24f.

[0116] In the example shown in FIG. 8, it is assumed that the power supply to the processor 21 is stopped at time t6. In this case, the clock signal CLK output from the processor 21 is stopped. Furthermore, the power supply state indication signal Vd output from the processor 21 goes low, and the abnormality detection signal Sa goes low. As a result, the control signals of the selector circuits 23a to 23c and 23d to 23f go low, and the input signal to the input terminal I2 is output from the output terminal O. Therefore, the signals output from the output terminal O of the selector circuits 23a to 23c go low.

[0117] Furthermore, the information latched in the buffering circuit 22 immediately after time t6 is the information latched immediately before time t6, and is at high level. Therefore, the signals output from the output terminals O of the selector circuits 23d to 23f are at high level. Since the clock signal CLK is stopped, no new latching is performed in the buffering circuit 22.

[0118] As a result of the above, the output signals of the selector circuits 23a to 23c become low level. Therefore, the signals input to the drive circuits 24a to 24c are low level, and the drive circuits 24a to 24c turn off the upper-stage switching elements 11a to 11c. Meanwhile, the output signals of the selector circuits 23d to 23f become high level. Therefore, the signals input to the drive circuits 24d to 24f are high level, and the drive circuits 24a to 24c turn on the lower-stage switching elements 11d to 11f. As a result, the active short circuit control is performed in the inverter 10, and the control method selected immediately before time t6 is continued.

[0119] (3) Other embodiments: The above embodiment is one example for carrying out the present invention, and various other embodiments are also possible. For example, various control methods can be selected as the normal control method, and various methods can be used to select the control method in fail-safe control. Furthermore, various methods can be used for the number and voltage of DC power supplies and the voltage of power to be supplied to each circuit. Furthermore, the use of the rotating electric machine 40 is not limited to driving a vehicle, and the rotating electric machine 40 can be used for various purposes. Furthermore, each circuit constituting the embodiment may be configured using either negative logic or positive logic.

[0120] The inverter includes a plurality of series circuits each including an upper-side switching element and a lower-side switching element, and these elements can convert power between a DC power source and an AC rotating electric machine. That is, the inverter can be a circuit capable of converting DC voltage and AC voltage using various known control methods (e.g., PWM control). The switching elements include an upper-side switching element and a lower-side switching element, and power can be converted between DC and AC by controlling the switching timing of these elements. Note that when the rotating electric machine is driven by multi-phase AC, there are multiple sets of DC circuits each combining an upper-side switching element and a lower-side switching element. For example, in the case of three-phase AC, there are three sets of combinations of an upper-side switching element and a lower-side switching element.

[0121] The control circuit may be any circuit that controls the inverter, and may include various circuits that control the inverter in addition to the processor, buffering circuit, and switching circuit.

[0122] The processor only needs to be able to cause the inverter to perform either shutdown control, which turns off all of the upper-stage switching elements and the lower-stage switching elements, or active short circuit control, which turns on one of the upper-stage switching elements and the lower-stage switching elements and turns off the other, depending on the rotational speed of the rotating electric machine. That is, the processor only needs to be able to cause the inverter to perform either shutdown control or active short circuit control depending on the rotational speed of the rotating electric machine, depending on a trigger to start fail-safe control. Of course, when a trigger to start fail-safe control has not been generated, the processor may perform normal control that is different from fail-safe control. Examples of normal control include switching between regenerative control and powering control depending on the accelerator pedal or brake pedal of the vehicle, gradient, etc.

[0123] The buffering circuit only needs to be able to buffer information indicating whether the control corresponding to the rotation speed of the rotating electric machine is shutdown control or active short circuit control, i.e., the buffering circuit only needs to be able to buffer information indicating the control selected by the processor before the power supply to the processor was stopped.

[0124] The configuration for buffering the information indicating whether the control is shutdown control or active short circuit control may be realized by a circuit other than the latch circuit described above. For example, in a configuration in which either the shutdown control or the active short circuit control is indicated by the voltage level output from the processor being either high or low, a capacitor may be provided to be charged by the voltage. With this configuration, it is possible to identify whether the control is shutdown control or active short circuit control based on whether the capacitor is charged.

[0125] Furthermore, the configuration for determining whether the currently executed control is the shutdown control or the active short circuit control is not limited to the configuration using the voltage output from the processor. For example, whether the currently executed control is the shutdown control or the active short circuit control may be determined based on the control mode of the upper-stage switching elements and the lower-stage switching elements by the drive circuit, the voltage, the current, etc. of the inverter.

[0126] The switching circuit may be configured to cause the inverter to perform control indicated by the information buffered in the buffering circuit when power supply to the processor is stopped. The switching circuit may be configured using any of various known selector circuits. The switching circuit may also be implemented by a logic circuit or the like that does not output a signal corresponding to the information buffered in the buffering circuit when power supply to the processor is stopped, but outputs a signal corresponding to the information buffered in the buffering circuit when power supply to the processor is stopped. [Explanation of symbols]

[0127] 10... inverter, 11a to 11c... upper stage switching elements, 11d to 11f... lower stage switching elements, 13a to 13f... diodes, 14... smoothing capacitor, 15... contactor, 20... control circuit, 21... processor, 22... buffering circuit, 23... switching circuit, 23a to 23c... selector circuits, 23d to 23f... selector circuits, 24a to 24c... drive circuits, 24d to 24f... drive circuits, 30... high voltage DC power supply, 32... low voltage DC power supply, 33... drive power supply circuit, 34... processor power supply circuit, 34a... AND gate, 40... rotating electric machine, 41... current sensor, 42... rotation sensor

Claims

1. an inverter including a plurality of series circuits each including an upper-stage switching element and a lower-stage switching element, for converting power between a DC power source and an AC rotating electric machine; a control circuit for controlling the inverter, The control circuit The inverter controls the rotation speed of the rotating electric machine according to the rotation speed of the rotating electric machine. a shutdown control for turning off all of the upper-stage switching elements and the lower-stage switching elements; an active short circuit control that turns on one stage of the upper stage switching element and the lower stage switching element and turns off the other stage of the upper stage switching element and the lower stage switching element; a processor that causes the processor to perform one of the following: a buffering circuit that buffers information indicating whether the control according to the rotational speed of the rotating electric machine is the shutdown control or the active short circuit control; a switching circuit that causes the inverter to perform control indicated by the information buffered in the buffering circuit when power supply to the processor is stopped; A rotating electrical machine control device comprising:

2. The processor: a high-level or low-level voltage is output from a predetermined output terminal to indicate whether the control according to the rotation speed of the rotating electric machine is the shutdown control or the active short circuit control; The buffering circuit a latch circuit that latches the voltage output from the predetermined output terminal; The rotating electrical machine control device according to claim 1 .

3. The control circuit a plurality of drive circuits for switching on and off the upper-stage switching elements and the lower-stage switching elements, The switching circuit For the drive circuit, a first signal output from the processor for controlling the inverter; a second signal output from the buffering circuit indicative of the buffered information; A selector circuit is provided to switch between the following inputs: The rotating electrical machine control device according to claim 1 or 2.

4. the buffering circuit supplies the second signal to either the drive circuit corresponding to the upper-stage side switching element or the drive circuit corresponding to the lower-stage side switching element, but does not supply the second signal to the other; The rotating electrical machine control device according to claim 3 .

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